ePoster #701 - ISHA Annual Scientific Meeting 2016

Do Patients with Bilateral FAI Have a Smaller Pelvic Incidence than Patients with Unilateral FAI?

Michael D. Hellman, MD, Chicago, IL UNITED STATES
Benjamin Kuhns, MD, Chicago, IL UNITED STATES
Bryan D. Haughom, MD, Chicago, IL UNITED STATES
Shane J. Nho, MD, MS, Chicago, IL UNITED STATES

Rush University Medical Center, Chicago, Illinois, UNITED STATES

FDA Status Not Applicable

Summary: Patients with bilateral symptomatic FAI appear to have a smaller PI than patients with unilateral symptomatic FAI.

ePoster Not Provided

Abstract:
Purpose:
Pelvic Incidence (PI) is a fixed anatomic parameter that plays an integral role in the sagittal balance of the spine. Recently, PI has been studied as it relates to femoracetabular impingement (FAI). It appears that a smaller PI is found in patients with symptomatic FAI. The purpose of this study was to compare the pelvic incidence in patients with unilateral symptomatic femoroacetabular impingement with the pelvic incidence in patients with bilateral symptomatic femoroacetabular impingement.

Methods:
We performed a retrospective analysis of 60 consecutive patients who had bilateral symptomatic FAI and 60 consecutive patients who had unilateral symptomatic FAI with computer tomography (CT) scans. PI was measured using the sagittal reformat. The center-edge angle (CEA), acetabular version, and a-angle were also measured. Demographic information including age and BMI was recorded. Our two groups were compared using a student t-test and a chi-squared test. An a priori power analysis showed that (1-ß) > 0.8 with 60 patients per group.

Results:
Both cohorts showed no difference in a-angle, CEA, acetabular version, age and BMI. The mean PI for the bilateral FAI group was 46.4°±9.5° (range, 28.4°-75.2°), less than the unilateral FAI group with a mean PI of 52.0±11.7 (range, 35.7°-79.5°) (p=0.006).

Conclusions:
Patients with bilateral symptomatic FAI appear to have a smaller PI than patients with unilateral symptomatic FAI. We hypothesize that because a smaller pelvic incidence restricts spinopelvic motion, the hip joint must increase its arc of motion to help facilitate changing positions. This motion restriction would equally affect both hips. This study helps prove this theory.